The wonders of Google! It struck me that the best way to find an analysis of the differences between AWM and AWM2 would be to find info about an early AWM2 device.

The TG55 was such a beast. Heres a link: http://homepage.mac.com/synth_seal/html/tg55.html

Thundering around the links on this site indicates that AWM is 12 bit whereas AWM2 is 16 bit. AWM2 also gains digital fitering.